If the success can be replicated in humans it may eventually lead to new treatments for glaucoma, the leading cause of irreversible blindness in the world, and other degenerative eye conditions by slowing sight deterioration, or reversing it altogether.

Scientists funded by the Medical Research Council (MRC) have successfully used adult human retinal stem cells to repair nerve cells damaged in glaucoma, partially restoring vision in rats.

If the success can be replicated in humans it may eventually lead to new treatments for glaucoma, the leading cause of irreversible blindness in the world, and other degenerative eye conditions by slowing sight deterioration, or reversing it altogether.

Glaucoma occurs when a build-up of pressure in the eye leads to the death of retinal ganglion cells (RGCs), which form the nerve fibers of the optic nerve and that transmit visual information from the eye to the brain. The condition can be treated in the early stages, but if diagnosis is late or treatment doesn’t work, damage to the eye cannot be reversed.

The researchers looked at whether injecting a type of adult human stem cell, known as the Müller glia stem cell, could stimulate repair of damaged RGCs in an animal model. Müller glia are found in the retina of humans and other vertebrates and are multipotent, meaning they can grow into any of the different nerve cells found in the retina.

The researchers used chemicals to induce Müller glia to grow into precursors of RGCs, before transplanting them onto the retinas of rats which had damage to their own RGCs.

After 4 weeks, the injected cells appeared to have formed new connections (synapses) with existing nerve cells and the rats had significantly improved retinal function when their vision was tested under very low light conditions. The scientists hope that, with further work, they will be able to develop new treatments to improve or restore vision in patients with untreatable glaucoma.

Dr. Astrid Limb, who led the study at the University College London (UCL) Institute of Ophthalmology, UCL, said:

“Although this research is still a long way from the clinic, it is a significant step towards our ultimate goal of finding a cure for glaucoma and other related conditions. We are optimistic that after further work on animal models to perfect our transplantation technique we will be in a good position to start early-stage clinical trials on humans in around 3 to 5 years.”

“The human eye is actually very efficient. We can still have fairly good vision with very few functioning retinal nerve cells, which is why many glaucoma patients don’t show symptoms until it is too late to treat the underlying cause of their vision loss. If we can restore even a small number of RGCs through cell therapy, and achieve functioning vision, we could potentially delay or even reverse blindness caused by glaucoma.”

Professor Peng T. Khaw, director of the National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields and the Institute of Ophthalmology and a co-author of the paper, said:

“These results are very exciting. We see patients with glaucoma whose lives would be transformed with an improvement of only a small percentage of nerve cell function. The results of these experiments suggest that this may be possible in the future using cells we all have in our own eyes to achieve this. Translational research like this gives hope to the many millions of people who have lost vision due to glaucoma.”

Dr. Rob Buckle, head of regenerative medicine at the MRC, said:

“Regenerative medicine is a key priority for the MRC and it’s wonderful to see another example of how our significant investment in stem cell research in recent years is beginning to deliver results. Repair of the eye is an area that is now at the forefront of this field, and this study highlights a new route for delivering the promise of regenerative medicine to treat disabling conditions such as glaucoma.”